Circuit interrupter



NOV. 30, s, T, SCHQFIELD ET AL 2,100,753

CIRCUIT INTERRUPTER Filed Dec. 24, 1935 2 SheetsSheet l F/g. Z.

WITNESSES: INVENTORS,

Samuel H. Baden and WM fifan/ey 7T Scho/fe/d.

7M1 Q, um-.4." BY V ATTOR EY 1937- S. T. SCHOFIELD ET AL 2,100,753

CIRCUIT INTBRRUPTER Filed Dec. 24, 1955 2 Sheets-Sheet 2 WITNESSES: INVENTORS.

Samue' B0 and W JM 5 7; I o/fe/a ATTOR EY Patented Nov. 30, 1937 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER East Pittsburgh, Pa.,

sylvania a corporation of Penn- Application December 24, 1935, Serial No. 56,072

17 Claims.

Our invention relates to circuit interrupters and particularly to high voltage-high capacity circuit breakers of the type which utilize a flowing stream of liquid for extinguishing the are or arcs formed incident to their operation.

The provision of a high speed circuit breaker suitable for use in high voltage interconnected circuits which are capable of delivering large amounts of power, is the principal object of our invention.

It has been conclusively proven by the experiments of a large number of independent investigators that an electrical circuit may be most eiliciently interrupted by drawing a relatively long are within an extremely short interval of time and subjectingthat arc to a flowing stream of cool, arc extinguishing liquid, which stream remains in close contact with the arc throughout its existence. In fact, if a sufiiciently long are 30 can be drawn and a substantial portion thereof subjected to such a flowing stream of liquid, extinguishment of that arc can usually be effected at the first zero point in the current wave, which of course is a most desirable condition for the reason that it results in the least possible disturbance to the associated equipment.

A further object of the present invention, therefore, is to provide means for rapidly lengthening the are formed incident to the opening 30 of the electrical circuit through an interrupter and for causing substantially the entire length of that arc to be subjected to the arc extinguishing action of a flowing stream of arc extinguishing fluid.

Another object of our invention, is the provision of a circuit interrupter wherein the movement of the movable contact member causes the are or arcs resulting from such movement to be subjected to a flowing stream of arc extinguishing liquid.

A still further object of our invention is to provide a simple, relatively inexpensive circuit Cal breaker which shall include means for simul-- (Cl. 200l50) more apparent in the following description of a preferred embodiment of our invention. Referring particularly to the drawings,

Figure 1 illustrates a single pole circuit interrupter embodying the features of the present invention.

Fig. 2 is an enlarged sectional view through the contact and are extinguishing structure of the breaker shown in Fig. 1. The view is taken on the line IIII of that figure.

Fig. 3 is an enlarged sectional view similar to Fig. 2, taken on the line IIIIII of Fig. 1.

Fig. 4 is a longitudinal sectional view of the structure shown in Figs. 2 and 3. This view is taken on the line IVIV of Fig. 2.

Fig. 5 is a detail plan view of one of the movable contact members forming a part of the structure illustrated in the preceding figures.

Fig. 6 is a fragmentary view of the upper portion of the contact and are extinguishing structure shown generally in Figs. 1 through 4.

Fig. 7 is a fragmentary perspective view of the operating shaft for the interrupter shown in Figs. 1 through 4, and

Fig. 8 is an enlarged detail view of one of the movable contact members utilized in conjunction with the breaker structure shown in the other figures of the drawings.

The circuit breaker proper, as is shown particularly in Fig. 1, includes a cylindrical tank I which is supported upon three symmetrically spaced insulator columns 3 and a removable cover 5 therefor. An insulating bushing 1 extends through a suitable opening formed in the cover 5 and is supported thereon by means of a flange 8 and a plurality of bolts Ill. The breaker contacts are actuated by the rotation of an operating shaft 9 which is supported upon the cover- 5 by means of a bearing Ii. The lower portion of this shaft 9 extends into the tank I and is provided with a tongue connection [3 for engaging the contact operating shaft I5.

A combined arc extinguishing and contact structure I1 is disposed within the tank I, and one end of this structure is electrically connected to the conductor l9 extending through the insulating bushing l by a suitable flexible lead 2|. The other end of the structure I! is electrically connected to the tank itself by a second suitable lead 23. The tank i thus comprises one of the terminals of the breaker and the conductor l9 extending through the insulating bushing 1 comprises the other.

The entire arc extinguishing and contact structure IT is normally submerged in a body of insulating liquid contained within the tank I. This liquid is preferably oil, because of'the very high are extinguishing ability of that fluid, but other insulating liquids may be used.

The arc extinguishing and contact structure I! comprises a stack of superposed plates 21 and 29 of insulating material which are assembled on four through bolts 3|. The structure itself is rigidly afixed to the base of the tank i by any suitable means. The plates 2'! and 29 are so formed and arranged that they provide a plurality of substantially cylindrical arc and contact chambers 33, and a pair of stationary contact assemblages is provided for each of these chambers.

A bridging contact 31 having the general form of a circular section of slightly less diameter than the cylindrical arc chambers 33 is provided for cooperating with each pair of the stationary contact assemblages 35, and during the operation of the interrupter, a pair of serially connected arcs are drawn within each of the arc chambers 33. The proportions of the movable bridging contact members 31 and the arc chambers 33 are so correlated that each of the bridging contacts 3'! acts as an impeller or piston member during each circuit opening operation thereby causing the quantity of the arc extinguishing liquid 25 nornially entrapped within each of the arc chambers 33 to be moved across the space between the arc drawing contacts.

As stated above, two types of plates are utilized in building up the arc extinguished portion of the structure ll. These plates are formed of insulating material, preferably hard fiber, both because of the high insulating qualities of that substance and because of its very considerable mechanical strength. Each of the plates 29, as is shown particularly in Fig. 2, has the central portion thereof cut away and serves to define the outer walls of one of the arc chambers 33. The top and bottom walls of each of the arc'chambers are defined by a p air'of the plates 21, shown in Fig. 3. The pkates 21 comprise cooperating half sections, in order to facilitate the assembling of the structure, and, except for the equally spaced holes which engage the supporting bolts 39 and the circular opening 33 in the central portion thereof which accommodate the contact operating shaft i5, are entirely solid. Each pair of the plates 21 is rotated 90 with respect to the structures adjacent set of plates in order to prevent the opening at the junction of those plates from forming a continuous passage through the entire structure.

Two outwardly projecting portions 5! are formed integral with each of the wall defining plates 29 for the purpose of providing a supporting means for :the'two stationary contact structures 35 which cooperate with the bridging contact member 37 movable within each of the arc chambe s.

5, as is illustrated particularly in Figs. 2 and 8, includes a spring biased movable contact 53 which is provided with a cylindrical body portion #35 adapted to slidably engage a cylindrical guide passage 31 formed within the cooperating wall defining plate 23. The inner or contact portion 43 of each of the movable contacts 53 is of less diameter than the body portion 55 in order to form a shoulder 59 which is adapted to abut against a cooperating shoulder 53 forming a part of the wall defining member 29, in order to define the limit of inward motion of the movable contact.

Each of the stationary contact The rear portion of each of the movable contacts 43 is likewise of reduced diameter in order 7 in the guide opening 41 by a screw plug 51 of insulating material. A flexible conductor 59 extends through each of the insulating plugs 51 and is soldered or otherwise mechanically and electrically connected to the associated movable contact member 43.

Each of the plate members 29 is also provided with three vent openings 6! disposed adjacent each of the stationary contact assemblages 35 supported thereon. These openings 5| prevent the building up of dangerous pressures within the arc chambers 33 during the operation of the interrupter, and also permit the arc extinguishing liquid 25 to flow freely into the arc chambers following each arc extinguishing operation.

Each of the bridging contacts'3l is preferably punched from a fiat sheet of conducting material of slightly less thickness than the plates 29 which define the outer wall of the cylindrical arc chambers 33 wherein the bridging contacts move, and the outlines of the contacts are such that each comprises a circular section of only slightly less diameter than the diameter of those chambers. Through this arrangement, each of the-bridging contacts 37 is caused to act as the piston or impeller during its rotation from the closed circuit to the open'circuit position, thereby moving a quantity of arc extinguishing liquid 25 between the are drawing surfaces, of the cooperating contacts. Each of the bridging contacts 31 is provided with a square opening 33 cut in the central portion thereof for engaging one of the square portions 65 of the contact actuating shaft I5, and is rigidly held in position upon that shaft by means of a screw 61 extending through a suitable opening formed in the central, side portion thereof.

By reference to Fig. 2, it will be seen that the contact portions 49 of the two stationary con-' tact assemblages 35 which are supported by each of the plates 29 engage diametrically opposed points on the cooperating bridging contact 3'! when the interrupter is in the closed circuit position. The contact surfaces of the bridging contacts 31 are so arranged that the movable contacts 43 which cooperate therewith are slidably moved a short distance into the guide passages 5'5 therefor during the closing operation of the switch. This assures a resilient engagement neautomatically compensates for wear of the contacts during the operative life of the interrupter. Inserts 39 of arc resisting conducting material are provided for the contact and arcing surfaces pair of cooperating contacts serially. Thus,dur- 7 ing the circuit opening operation, the electrical circuit through the interrupter is simultaneously opened at a plurality of points. In the particular structure illustrated in the drawings with 8 bridging contacts, the circuit is opened at 16 points simultaneously, and since each of the 16 arcs resulting from this circuit opening movemnt is lengthened simultaneously with the other arcs, an extremely rapid are drawing operation is effected by even a comparatively slow movement of the contact actuating shaft l5.

The interrupter is shown in the closed circuit position in Fig. 2. During each opening operation, the contact actuating shaft i5 is rotated in a counter-clockwise direction so as to move all of the bridging contacts 31 simultaneously from the position shown in full in Fig. 2 to the position indicated by the dot and dash lines of that figure. As mentioned previously, this movement opens the electrical circuit through the interrupter at some 16 points and effects the simultaneous drawing of the same number of serially connected arcs. Further, since the physical dimensions of each of the bridging contacts 31 are only slightly less than the physical dimensions of the arc chambers 33 wherein those contact members move, each of the arcs is individually subjected to the action of a separate, transversely flowing stream of arc extinguishing liquid, which streams are set in motion by the piston or impeller action of the moving bridging contact. The combined result of this extremely rapid drawing of a plurality of serially connected arcs and the subjecting of each of those arcs to a flowing stream of arc extinguishing liquid, is to assure the rapid opening of the circuit controlled by the interrupter, even under the most adverse operating conditions. The high efficiency of arc extinction is brought about both by the large separation of the cooperating are drawing contacts as the interrupter moves to the open circuit position and by the fact that a quantity of fresh oil or other arc extinguishing liquid is moved between each pair of the are drawing surfaces during each operation of the interrupter.

From the foregoing it will be apparent that the circuit interrupter of our invention may be assembled by building up a plurality of plate sections, each of which can be readily punched by well known punching operations, thereby providing a simple structure which may be readily disassembled for servicing or maintenance.

In accordance with the patent statutes, we have thus disclosed the features of one of the preferred forms of our invention. It is to be understood, however, that many of these features are merely illustrative and that variations in their precise form will be both necessary and desirable in certain instances. It is our intention, therefore, that the language of the accompanying claims shall be accorded the broadest reasonable construction and shall be limited only by what is expressly stated therein and by the prior art.

We claim the following as our invention:

1. In a circuit interrupter, means, at least partially of insulating material, for defining the walls of an arc chamber which is substantially cylindrical in form, a rotatable shaft extending through said are chamber in such manner that the axis of rotation thereof substantially coincides with the axis of said are chamber, a quantity of arc extinguishing liquid contained within said arc chamber, means for opening and for closing the electrical circuit through said inter;

rupter, said means causing the are or arcs incldent to the opening of said interrupter to be established within said are chamber, a piston or impeller member, the cross sectional outline of which comprises a circular section of only slightly less diameter than the diameter of said arc chamber, supported on said shaft for rotation within said are chamber, and means for rotating said shaft and said piston or impeller member during each opening operation of said interrupter, in order to move a quantity of said are extinguishing liquid across the arc path or paths.

2. In a circuit interrupter, means at least partially of insulating material for defining the walls of an arc chamber which is substantially cylindrical in form, a rotatable shaft extending through said are chamber in such manner that the axis of rotation thereof substantially coincides with the axis of said arc chamber, a quantity of arc extinguishing liquid contained within said are chamber, a stationary contact means, and a movable contact means for cooperating therewith to open and to close the electrical circuit through said interrupter, said movable contact means including a contact carrying member, the cross sectional outline of which comprises a circular section of onlyslightly less diameter than the diameter of said are chamber, supported on said shaft for rotation within said are chamber to effect the operation of said interrupter and to establish the arc incident to each opening operation thereof within said are chamber, the arrangement of said cooperating contact means and the physical proportions of said contact carrying member and said are chamber being so correlated that said contact carrying member acts as a piston or impeller during each opening operation of said interrupter in order to move a stream of said are extinguishing fluid between the are drawing surface of said contact means.

3. In a circuit interrupter, means at least partially of insulating material for defining the walls ofan arc chamber which is substantially cylindrical in form, a rotatable shaft extending through said are passage in such manner that the axis of rotation thereof substantially coincides with the axis of said are chamber, a quantity of arc extinguishing liquid contained within said are passage, a stationary contact means, including a pair of's'tationary contacts positioned substantially at diametrically opposite points in the walls of said arc chamber, and a movable contact means for cooperating with said stationary contact to open and to close the electrical circuit through said interrupter, said movable contact means including a bridging member, the cross sectional outline of which comprises a circular section of only slightly less diameter than the diameter of said are chamber, supported on said shaft for rotation within said are chamber, said bridging member causing the establishing of at least two serially connected arcs within said are chamber during each circuit opening operation and coacting with said are chamber in such manner to force a stream of said arc extinguishing fluid during each opening operation of said interrupter between each pair of cooperating contacts.

4. In a circuit interrupter, a plurality of sta tionary contacts, a rotatable shaft, which is formed at least partially of insulating material,

a plurality of movable contact carrying members supported at spaced intervals on said shaft, said contact carrying members'having movable contacts thereon for cooperating with said stationary contacts, means for interconnecting said stationary and said movable contacts in such manner that a plurality of serially connected arcs are simultaneously established during each opening operation of said interrupter, a quantity of arc extinguishing liquid, and means for defining a plurality of separate arc chambers within each of which one of said movable contact carrying members is adapted to move in response to the rotation of said shaft and within each of which at least one of said serially connected arcs is established, the physical proportions of said are chambers and said contact carrying members movable therein being so correlated that each of said contact carrying members acts as a piston during each circuit opening operation of said interrupter to move a quantity of said are extinguishing liquid into the path of each of said serially connected arcs.

5. In a circuit interrupter, means at least partially of insulating material for defining the walls of a plurality of spaced, separate substantially completely enclosed arc chambers, means for establishing a plurality of serially connected arcs during each opening operation of said inter- V 'rupter, at least one of said arcs being established within each of said are chambers, a quantity of arc extinguishing liquid normally contained within each of said arc chambers, a piston or impeller member closely fitted within each of said are chambers and movable during each circuit opening operation to positively move a quantity of said liquid into the path of the arc or arcs established therein and unitary means for simultaneously actuating said piston members.

v6. In a circuit interrupter, a structure comprising a. plurality of superposed plates at least some of which are of insulating material for defining a plurality of spaced, separate substantially completely enclosed arc chambers, means for establishing a plurality of serially connected arcs during each opening operation of said interrupter, at least one of said arcs being established within each of said arc chambers, a quantity of arc extinguishing liquid normally contained within each of said are chambers, a piston or impeller member closely fitted within each of said are chambers and movable during each circuit opening operation to positively move a quantity of said liquid into the path of the arc or arcs established therewithin and unitary means for simultaneously actuating said piston members.

7. In a circuit interrupter, a structure comprising a plurality of superposed plates, at least some of which are of insulating material, for defining a plurality of spaced separate substantially completely enclosed arc chambers, a quantity of arc extinguishing liquid normally contained within each of said chambers, and a plurality of pairs of serially connected contacts for establishing a plurality of serially connected arcs during each opening operation of said interrupter, one of each of said pairs of contact members being supported by a piston or impeller member closely fitted within one of said are chambers and movable therein to draw at least one of said plurality of serially connected arcs therein and to positively move a quantity of said are extinguishing liquid into the path of the are or arcs established thereby.

8. In a circuit interrupter, an arc extinguishing structure comprising a stack of superposed plates of insulating material, some of said plates having centrally disposed cutout portions formed therein for defining a plurality of substantially completely enclosed arc chambers, a quantity of arc extinguishing liquid within which said structure is normally submerged, a plurality of pairs of serially connected contacts for establishing a plurality of serially connected arcs during each opening operation of said interrupter, one of each of said pairs of contacts projecting into each of said are chambers, and the other of each of said pairs of contacts being carried by a rotatably supported piston or impeller member closely fitted within one of said are chambers and movable to draw at least one of said plurality of serially connected arcs therein and to positively move a quantity of said are extinguishing liquid into the path of the are or arcs established thereby and common means for simultaneously actuating said piston members.

9. In a circuit interrupter, means defining an arc chamber, an arc extinguishing fluid in said chamber, a pair of spaced stationary contacts within said chamber, bridging contact means for completing the circuit between said spaced contacts, a, movable member for carrying said bridging contact means and disposed between said stationary contacts to divide said are chamber into two compartments, and means for moving sa d movable member to establish an are between said stationary contacts and said bridging contact means in each of said compartments, said movable member being disposed with respect to said chamber and said contacts that upon movement thereof to cause an opening of said contacts a quantity of said are extinguishing fluid is propelled by said member between said contacts and said bridging contact means.

10. In a circuit interrupter, means defining an arc chamber, a stationary contact in said chamber, a contact carrying member having a movable contact thereon adapted to be moved by said member into and out of engagement with said stationary contact, means along the walls of said chamber which gives oif a gas when acted upcn by an arc to aid in the extinguishing of an arc, said are chamber having venting means for the escape of fluid therefrom, said contact carrying member being disposed in said chamber to substantially cover said venting means when the member is in the closed circuit position, and means for moving said contact carrying member to establish an are between said contacts and to uncover said venting means, the venting capacity of said venting means being controlled only by the movement of said contact carrying member.

11. In a circuit interrupter, means defining a substantially cylindrical arc chamber, a pair of spaced diametrically opposed stationary contacts within said chamber, a rotatably mounted piston member disposed between said contacts to divide said chamber into two compartments, movable contacts carried by said piston member adapted to cooperate with said stationary contacts for establishing and interrupting the circuit therebetween, a material along the walls of said chamber which gives ofi a gas when acted upon by an arc to aid in the extinguishing of the are, said chamber defining means having vent openings for each compartment, said piston member being disposed to substantially close said vent openings when said member is in the closed circuit position, and means for rotating said piston member to establish an are between the cooperating contacts in each compartment and to uncover said vent openings.

12. In a circuit interrupter, means defining a substantially cylindrical arc chambena pair of use spaced diametrically opposed stationary contacts within said chamber, a rotatably mounted piston member disposed between said contacts to divide said chamber into two compartments, movable contacts carried by said piston member adapted to cooperate with said stationary contacts for establishing and interrupting the circuit therebetween, a liquid within said chamber which gives oil a gas when acted upon by an arc to aid in extinguishing the arc, said chamber defining means having vent openings for each compartment to enable the escape of fluid therefrom, said piston member being disposed to substantially close said vent openings when said member is in the closed circuit position, and means for rotating said piston member to establish an are between the cooperating contacts in each compartment and to uncover said vent openings, said rotating piston member torcing a quantity of said liquid between each pair of said cooperating contacts to aid in extinguishing the arcs therebetween.

13. In a circuit interrupter, means at least partially of insulating material defining a substantially completely enclosed arc chamber, a stationary contact in said arc chamber, a contact carrying member having a movable contact thereon adapted to be moved by said contact carrying member into and out of engagement with said stationary contact, an arc extinguishing liquid within said are chamber and means for moving said contact carrying member to establish an arc between said contacts, said contact carrying member being closely fitted within said are chamber to positively move a quantity of said are extinguishing liquid between said contacts during movement of said movable contact to the open circuit position.

14. In a circuit interrupter, means at least partially of insulating material defining a substantially completely enclosed arc chamber, a stationary contact in said arc chamber, a contact carrying member having a movable contact thereon adapted to be moved by said contact carrying member into and out of engagement with said stationary contact, an elongated arc terminal member adjacent each of said contacts, an arc extinguishing liquid within said are chamber, means for actuating said contact carrying member to establish an are between said contacts, said contact carrying member being closely fitted within said arc chamber to positively move a quantity of said are extinguishing liquid between said contacts for moving said are laterally onto and along said arc terminal members.

15. In 'a circuit interrupter, means at least partially of insulating material defining a substantially completely enclosed arc chamber, a stationary contact in said are chamber, a contact carrying member having a movable contact thereon adapted to be moved by said contact carrying member into and out of engagement with said stationary contact, an elongated arc terminal member adjacent each of said contacts, an arc extinguishing liquid within said arc chamber, means for actuating said contact carrying member to establish an arc between said contacts, said contact carrying member being closely fitted within said are chamber to positively move a quantity of said are extinguishing liquid between said contacts for moving said are laterally onto and along said arc terminal members, said are chamber having vent openings leading therefrom for the escape 01' the products of decomposition of the arc.

16. In a circuit interrupter, means at least partially of insulating material defining a narrow substantially completely enclosed arc passage, a stationary contact within said are passage, 9. cooperating movable contact within said are passage adapted to be moved to open and closed positions, a pair of arc horns each one of which has one end adjacent a respective contact, an arc extinguishing liquid within said arc passage, means for actuating said movable contact to the open position, a piston member closely fitted within said arc passage movable in accordance with the movement of said movable contact for positively moving a quantity of said are extinguishing liquid against said arc to move it laterallyalong said arc horns and vent means adjacent the other end of at least one of said are horns to permit the escape of the products 01' decomposition of said are from said arc passage.

17. In a circuit interrupter, means at least partially of insulating material defining a narrow substantially completely enclosed arc passage, a stationary contact within said are passage, a cooperating movable contact within said arc passage adapted to be moved to open and closed positions, a pair of arc horns each one of which has one end adjacent a respective contact, an arc extinguishing liquid within said are passage, means for actuating said movable contact to the open position, a piston member closely fitted within said arc passage movable in accordance with the movement of said movable contact for positively moving a quantity of said arc extinguishing liquid against said arc to move it laterally along said are horns, and vent openings leading through said are passage defining means, said piston member substantially covering said vent openings when said movable contact is inthe closed position, the eflective area of said vent openings being controlled only by the movement of said piston member.

STANLEY T..SCHOFIELD. SAMUEL H. BODEN.

DI SC LAI M E R 2,100,753-.Stanley T. Schofield, Wilkinsburg, and Samuel H. Baden, Turtle Creek,

Pa. CIRCUIT INTERRUPTER.

Patent dated November 30, 1937. Disclaimer filed August 26, 1938, by the assignee, Westinghouse Electric &: Manufacturing Company.

Hereby enters this disclaimer to claim of the patent specification.

[Oflic'ial Gazette September 13, 1938.] 

